Skip to main content

Full text of "Discovering Fire Island: The Young Naturalist's Guide to the World of the Barrier Beach"

See other formats

jtarty 21 

<i"n r 





Fire Island 

The Young Naturalist's Guide to the 
World of the Barrier Beach 


v V* 


Fire Island National Seashore was estab- 
lished to preserve the plant-and-animal 
communities of one of the few relatively 
unspoiled barrier beaches on our Atlantic 
coast. Within the boundaries of the National 
Seashore, the National Park Service not 
only provides for a variety of recreational 
activities but protects the natural resource 
as an outdoor laboratory for the study of 
geology, biology, and ecology. Except for 
those living things officially authorized for 
harvesting (fish, clams, etc.), and nonliving 
things such as shells and other beach 
wrack, do not remove anything from the 
park without permission. 



Fire Island 



The Young Naturalist's Guide to the 
World of the Barrier Beach 

by Bill Perry 

drawings by Michael Graham and Missy Lipsett 

Division of Publications 
National Park Service 
^ U.S. Department of the Interior 




A Ramble Across the Barrier Island 





Birth of a Barrier Beach 



How to Be a Beachcomber 



Your Beachcombing Kit 






Mole Crabs 



Razor Clams 



After the Storm 



Up and Down in the Dune and Swale Zone 



What's in a Name? 



Natural Communities 


Food Chains 


Mysteries of the Maritime Forest 






Wet Your Feet in the Salt Marsh 



What Good is a Salt Marsh? 



Natural Succession 



Who's Who in the Zostera Community 



The Eelgrass Blight 






Reading List 


A Living Fossil: I 
Beachcombers All: I 
Be a Scavenger: G, I, T 
Sunlight and Sand: I 
Osmosis: G, / 

Profiling a Community: /, G 
Comparing Communities: A, I, T 
Backyard Ecology: I, G, T, Y 
The Eelgrass Microhabitat: I 
The Web of Life: G, I, A, T 

Maps and Diagrams 

The Middle Atlantic Coast 
The Origins of Fire Island 
Cross-section of Fire Island 
The Maritime Forest 
Food Web of the Salt Marsh 
The Zostera Community 


Explorations Key: 

A: For advanced ecology 

I: Individual explorations 

G: Group explorations — direct 
supervision of a teacher or 
leader required for beginners 
or younger students. 

T: Team explorations — 2 to 6 
students or a family 

Y: Investigations to be carried on 
at intervals over a period of at 
least one year, or during the 
same season in successive 


Thanks are due the following persons who helped in 
the preparation of this book: Superintendents James W. 
Godbolt and Richard W. Marks of Fire Island National 
Seashore; Interpretive Specialists Pat Crosland and 
Neal R. Bullington; numerous members of the park staff 
who provided information and transportation; and 
William H. Amos, who reviewed the manuscript and 
gave much valuable advice. 

Photo Credits 

William H. Amos: pp. 37, 43, 47, 78, 79; Richard Frear: 
pp. iv, 8, 18, 28, 55, 67, 76; Luther C. Goldman: p. 75; 
Bill Perry; pp. 4, 5, 9, 12, 15, 21, 32, 34, 40, 41, 46, 47, 
48,49, 51, 52, 62, 64; Rex Schmidt: p. 2. 





^ z - 


A Ramble Across the 
Barrier Island 

Across Great South Bay, the sun appears about to sink 
into the low mass of Long Island. You are wading 
among patches of eelgrass in the warm, shallow water 
off the north shore of Fire Island. Dipnet in hand, you 
are seeking whatever kind of animal life you can cap- 
ture. The fingersize fish darting about your legs are too 
fast. But wouldn't it be a thrill to see a sea horse? Your 
chances are slim. This animal is a slow swimmer, but 
it is not abundant, and it is well camouflaged in its 
eelgrass-jungle habitat. You do manage to catch a few 
crabs, dig up one clam with your toes, and scoop a 
number of small crustaceans into your fine-mesh net. 

Suddenly an enormous horseshoe-crab comes right 
toward you, swimming just under the surface and veer- 
ing to one side as it is about to bump your legs. Ex- 
citedly, you grab it by the long tail spine, drag it to 
the beach, and turn it over for a close look. What a 
curious creature! As it attempts to right itself with its 
tail, you probe between the leaflike "book gills" on its 
underside. There you find just what you're looking for: 
a large white flatworm, a permanent guest of the horse- 
shoe-crab, living on the gills with no evident harm to 
the host. Turning the big invertebrate right-side up, you 
watch it return to the water. How does it find its way so 
easily? You didn't notice any eyes. 



The flatworm, 
Bdelloura (don't pro- 
nounce the "B"), 
lives on the gills of 
the horseshoe-crab. 



The horseshoe-crab, Limulus polyphe- 
mus, is actually an arachnid, related to 
spiders, ticks, scorpions, and daddy- 
long-legs. This non-crab plows the 
muddy and sandy bottoms in search of 
the burrowing animals upon which it 
feeds. In early summer it lays its eggs 
in the sand along the shore. Horseshoe- 
crabs often carry a bevy of passengers 
— permanent guests, not hitchhikers — 
including sea lettuce, barnacles, boat 
snails, tube worms, limpets, and flat- 
worms. Limulus is valuable to science: 
blood is drawn from living specimens 
(without killing them) and used in medi- 
cal diagnosis. Return the horseshoe-crab 
unharmed to its habitat. 

As the horseshoe-crab swims away, your thoughts 
wander back in time — for you have just had a brush 
with the world of 200 million years ago, when such 
marine monsters as Ichthyosaurus ruled the seas, long 
before the great predatory dinosaur, Tyrannosaurus, 
appeared on land. This horseshoe-shaped animal with- 
out a backbone but with a tanklike outside armor has 
lived in Earth's seas virtually unchanged since that era. 
No wonder it is called a living fossil! 

On the narrow beach you discover that the tide, reced- 
ing while you foraged in the bay, has deposited a 
wealth of beachcomber's treasure on the sand. Here's 
an assortment of flotsam, jetsam, and beach wrack that 
could occupy you for hours. Besides a few dead horse- 
shoe-crabs and many shed exoskeletons, there are 
scallop shells, seaweeds of various shades of brown 
and red, assorted driftwood, various items discarded 
from boats, and an abundance of plastic bottles and 
other ugly reminders that civilization is close by. 

More interesting to you right now is a set of hoofprints 
running along the high-tide line. A deer has chosen the 
easy travel route; passage down the middle of this long, 
narrow, roadless island is made difficult by dense 
thickets of trees and shrubs. You decide to follow the 
deer tracks to see if they'll lead to an island crossing. 

The American goosefish, Lophius ameri- 
canus, Is so soft-bodied that when it is 
stranded on the shore its flat body be- 
comes even flatter. It is one of the 
angler fishes, and although it preys on a 
wide variety of marine animal life it 
sometimes lies in wait in the eelgrass 
and gulps down fish that approach its 
lure — a flap of skin at the tip of the 
spine over its great mouth. 

A Living Fossil: I 

Examine the external anatomy of 
Limulus, the horseshoe-crab. You 
will notice that it resembles the hoof 
of a horse rather than a horseshoe; 
probably it was originally named 
"horsefoot-crab." Locate the eyes. 
How many are there? How does 
their position relate to Limulus' 
feeding habits? Study the book gills 
and swimming appendages. (Later, 
find a diagram of the gillbooks of a 
spider for comparison. And see if 
you can find out how Limulus, which 
has no jaws, chews its food.) 

Examine the exoskeleton. Can you 
find the opening through which the 
horseshoe-crab emerged from its 
outgrown armor? Except for this slit 
around the front margin, your speci- 
men will be a complete and accu- 
rate representation of the exterior of 
the animal. 

A little way along the beach you come to the skeleton 
of a goosefish, more than a meter long and almost as 
wide. You can well believe the account of a goosefish 
that was found to contain the bodies of seven ducks! 
Nearly all gaping mouth, with a formidable array of 
teeth, it seems a monster indeed. But there is a natural 
function for each of its parts, including the great mouth. 
Perhaps to a goosefish you would appear as grotesque. 

There is still flesh and skin adhering to the bones and 
skull of the goosefish, and it emits a putrid odor. But 
thinking that the skeleton would make a great conver- 
sation piece for your bedroom, you drag it to the upper 
beach to leave for the gulls, grackles, and scavenging 
invertebrates to clean up. You can return for your 
specimen in a few days. 

Now the deer tracks turn inland, following a path 
through the salt marsh that separates the bay and the 
forest. Perhaps this will lead to the ocean beach. Fol- 
lowing the trail, you pass first through a ten-meter-wide 
forest of reeds that tower high above you with large, 
feathery tips waving gracefully in the evening breeze. 
Beyond this zone of tall grasses is a band of ankle-high, 
odd-looking plants with fleshy stalks and without no- 
ticeable leaves or flowers. They look much like the 
primitive horsetails — the plants your pioneer forebears 

called "scouring rushes" and used for cleaning pots. 

The glasswort zone merges eventually into a growth of 
head-high bullrushes; a little farther on the bullrushes 
mix with high shrubs whose big, pinkish blossoms 
remind you of the hibiscus growing back home in the 
front yard. Perched on the swaying tip of one of the 
tallest of these plants is a male red-winged blackbird, 
calling "konk-la-ree! konk-la-ree!" 

Your nose wrinkles, and you stop. What is that odor 
that reminds you of a disagreeable medicine? It seems 
to be coming from some hip-high plants with purplish 
flower clusters. You think, "stinkweed" would be a 
good name for them. 

Phragmites is perhaps the tallest of the 
grasses, with the exception of the 
bamboos. It grows in both fresh and 
brackish water, normally to a height of 
3 or more meters; sometimes it towers 
to almost 6 meters. It adds picturesque 
beauty to the lagoons and estuaries, and 
its strong root system helps control ero- 
sion on barrier islands and estuaries; 
but it encroaches on good wildlife 

Indians taught us 
to make a bever- 
age from sassa- 
fras. It is more 
important ecologi- 
cally as a "pio- 
neer" tree: in 
some areas it is 
one of the first 
species to come 
into a burned or 
abandoned field. 

Glasswort (Salicornia europaea), despite 
its resemblance to the horsetails, is ac- 
tually a member of the goosefoot family. 
Glasswort grows in coastal marshes 
over most of the world. Like spinach and 
the common garden pest, pigweed, 
which are members of the same family, 
it is quite edible. 

The forest is now only a few steps away. At the border 
of forest and marsh you see the plant you've been 
warned to watch for: poison Ivy. Tracks and droppings 
indicate that the deer lingered here, as if to feed. Could 
it be that this plant, so troublesome to humans, actually 
provides nourishment for wild animals? 

In the diminishing light of early evening, you move into 
the forest on a boardwalk trail. You stop, turn down the 
legs of your jeans, and apply insect repellent to your 
exposed skin; for there is little breeze here to discour- 
age the mosquitos. As they fly about your head, you 
wonder what possible good there can be in these pesky 
creatures. True, they are food for swallows and dragon- 
flies. If only they'd leave you out of the food chain! 

What an unusual forest this is. There are no tall trees; 
you estimate that the biggest in sight is only seven 
meters high, although at the level of your eyes the 
trunk is almost as big around as your body. Another 
tree here has a very familiar look — it's the leaves, 
shaped like mittens, some with no thumb, some with 
one, some with two. You crush one of the leaves and 
hold it to your nose. Sure enough, there's no mistaking 
the fragrance of sassafras. 


Imagine a fish with a tubelike mouth through which it 
sucks its food as through a straw, a pouch in the male's 
abdomen in which the young hatch and remain until they 
are ready to make it on their own, an armor of interlocking 
bony plates instead of scales, and the ability to change 
color to blend with its surroundings; an animal that swims 
in a rigid upright position with no body movement and just 
a faint fanning of the delicate fins, uses its prehensile tail 
like a South American monkey's to cling to its slippery 
eelgrass perch, and resembles some mythical creature, 
half-horse, half-mermaid. Such a creature is the sea horse, 
Hippocampus. Though its appearance and behavior 
wouldn't make you think so, it is a true fish, having a bony 
skeleton and occupying a rung on the evolutionary ladder 
about halfway between the primitive lungfishes and the k 
highly advanced flounders and mackerel. 

Irresistible is the word for this quaint creature. Lacking 
the streamlining of most fishes, it seems to defy the laws 
of hydrodynamics as it swims stiffly upright. No wonder it 
depends upon camouflage instead of speed for protection 
from its enemies. It captures its prey, which is chiefly small 
crustaceans and crustacean larvae, not so much by pur- 
suit as by vigorously sucking in what comes close. It 
apparently spends most of its time clinging to underwater 
rooted or free-floating plants, where its visibility is low and 
the food supply good. Look for it on the bay side of Fire 
Island in the eelgrass meadows under a meter or more of 
water. Finding one will be largely a matter of luck, for 
these animals apparently disappeared from these coastal 
waters with the decline of the eelgrass beds in the early 
1930s (see p. 86) and are just now on the comeback road 
long after the eelgrass returned. 

Would sea possum or sea kangaroo be a better name 
for it? 


The forest is alive with birds. You see such fruit-eating 
species as robins, townees, catbirds, and thrashers. 
You recognize the juneberry trees, having enjoyed their 
fruit on many a hike in the countryside. Here there are 
also the abundant fruits of black cherry, holly, choke- 
berry, and sassafras. 

Poison-ivy is scattered through the forest, making you 
thankful for the elevated trail. Eventually the winding 
boardwalk leads out of the dimness to the top of a high 
dune. You can now hear the surf. You are at the border 
of the dune-and-swale community. Beyond the fore- 
dune a hundred meters away will be the ocean beach 

Turning around, you get a tern's-eye view of the forest 
you've just left. Looking down on the roof of the densely 
shaded community, one might think, "Why, it's almost 
like a green carpet I could walk across!" The foliage is 
so thick that you can see nothing under the top layer, 
and for all one could tell from this viewpoint, it might 
be no taller than your knees. What pruning tool has 
kept this forest leveled to the height of the dunes that 
separate it from the ocean beach? 



Rhus toxicodendron, poison-ivy, related 
to cashew and pistachio but not to Eng- 
lish ivy, grows as a woody shrub or vine. 
Its three-parted leaves are borne alter- 
nately on the stem. It is common on Fire 
Island — so know it, use established 
trails, and keep alert. 

Everybody's favorite reptile, the box tur- 
tle (Terrapene Carolina) ranges as far 
north as Maine and Michigan, as far 
south as Florida, and west of the Mis- 
sissippi as far as central Kansas. It's as 
wide-ranging in its diet, which includes 
mushrooms, snails, insects, berries, and 
earthworms. The female's eyes are nor- 
mally brown; if you see a red-eyed box 
turtle, it's most likely a male. The plas- 
tron (lower shell) of the male is concave. 

Glancing down, you see a box turtle on the sand by a 
poison-ivy plant. It's a surprising place to see a turtle, 
even a land species. You'd have expected it in the 
damper low spots of the forest — but here, on the sun- 
baked top of the dune? 

Before you a broad hollow, extending to your right and 
left as far as you can see, separates your dune from the 
dune that borders the beach. The vegetation in this 
zone is neither as dense nor as tall as that in the forest 
you've just left. Junipers, hollies, and pitch pines, 
pruned to the contours of the dune, cover the top of the 
dune; but as you go down the face these give way to a 
variety of plants growing in low clumps separated by 
bare sand. One shrub, with dense clusters of small, 
white flowers like wild roses, catches your eye; it's the 
same plant from which, on a September weekend, you 
gathered beach plums for home-made jelly. It has two 
growth forms here — sprawling on the ground and 
standing upright. A few meters away a cottontail is 
nibbling on one of these shrubs. 


Suddenly a mallard duck zooms in over your head and 
makes a landing in the midst of the brushy vegetation. 
This is a strange habitat for waterfowl, you think. On 
the other hand, there would certainly be good hiding 
places for a nest under the thick clumps of shrubs and 
sprawling pitch pines. 

Continuing on the boardwalk across the swale, you 
reach the top of the dune bordering the beach — 
the primary dune, or foredune. It slopes steeply to the 
high-water mark, and here the woody plants have given 
way almost entirely to clumps of beach grass. 

The breeze is stronger than it was on the bay side of 
the island, and you can feel salt spray on your face. The 
cries of wheeling gulls and terns pierce the rhythmic 
roar of the surf. Two herring gulls are foraging for food 
at the line of wave upwash. What is the sea bringing to 
them? The graceful, hovering terns drop at intervals to 
the surface beyond the breakers; whatever they're fish- 
ing for must be small, for you can't see anything in 
their beaks. 

You, too, are lured to the beach. Removing your shoes 
and again rolling up your jeans, you run down the 
broad slope toward the water. Suddenly three small, 

sand-colored birds you hadn't noticed fly up in front of 
you and settle again on the sand about 30 meters down 
the beach. As the waves wash up the beach, the little 
birds dash back and forth almost as if playing tag with 
the water; but as they follow each receding wave they 
jab their bills repeatedly into the sand. You walk toward 
them, hoping to get close enough to see what they're 
picking up. Again they fly up, white wing-bars flashing, 
to land a safe distance away and resume their game 
of catch-me-if-you-can with the waves. 

For a while you try the same sport; you soon discover 
that it's impossible to predict how far each wave will 
run up the beach. Standing still, you enjoy the sensa- 
tion of having the receding waves wash the sand out 
from under your feet. Would you sink out of sight if you 
stayed long enough? How quickly your footprints dis- 
appear when you walk away! This must be a difficult 
environment for animals. You wonder how the birds can 
expect to find living things in these shifting sands. 
With such questions in mind, you decide to come back 
tomorrow with a digging tool. But now the sky is dark- 
ening rapidly, for the sun is well below the horizon. 
Buttoning your windbreaker, you gather up shoes and 
equipment and walk along the beach toward camp. 


* Jttk 

Birth of a Barrier Beach 

To retrace the origin and growth of Fire Island, we must 
go back many thousands of years — to the Pleistocene, 
long before the birth of the island. During that epoch 
great ice sheets moved a number of times far down into 
the continents of the Northern Hemisphere. The last of 
these advances almost reached the point where Fire 
Island is now located. Great masses of rock material 
borne in and on that glacier were carried by glacial 
streams far beyond its terminus. The rocks, silt, and 
sand were deposited by the streams in fan-shaped 
formations. A long row of these "outwash fans" — so 
close together that they overlapped — was the founda- 
tion for most of Long Island. 

About 11,000 years ago, the ice sheet began to melt 
rapidly. The mainland at that time extended south 
beyond today's beaches; Long Island was then only a 
low ridge on the outwash plain, and Long Island Sound 
a river valley in the plain. So much of Earth's water was 
tied up in the ice sheets that the ocean was a hundred 
or so meters lower than it is today. But as the ice 
melted, sea levels rose. By about 4,000 years ago they 
reached the level of today. The ridge became Long 
Island as the sea moved into the valley and separated 
it from the mainland. The south shore of Long Island 
.„ between Montauk Point and Southampton was at this 





Cape Cod 


Long Island 
"ire Island 



Limit of glacial advance 

time about 2 kilometers beyond its present location. 
Thus the stage was set for the long process that cul- 
minated in today's Fire Island. (Keep in mind that the 
process is still occurring, that Fire Island is a dynamic, 
not a static, geologic feature.) 

How did the Long Island shoreline move back to this 
point, and how did Fire Island develop where the main- 
land formerly existed? The name of the game, you 
might say, is "Erosion and Deposition." The tools used 
to play the game were wind, waves, and currents. 

The Middle Atlantic Coast 

Long Island, its barrier beaches, and 
Cape Cod all owe their existence to the 
Pleistocene glaciers; but the barrier 
beaches to the south consist largely of 
sand carried down by rivers from 
eroding mountain ranges. 

Barrier islands, as we call these wave-and-current- 
built, linear islands, are developed only where the land 
slopes gently beneath the sea. Here the glacial outwash 
plain extended well out beyond the shoreline as the sea 
rose and advanced landward. Under such conditions, 
winddriven ocean waves pick up sand from the shallow 
bottom and build it into an underwater ridge, or sand 
bar. With the help of longshore drift (see p. 16), the bar 
is built up above sea level, and we have what we some- 
times call a barrier beach, separated from the mainland 
by a shallow bay, or lagoon. (Long Island is Fire Is- 
land's "mainland," and Great South Bay is its lagoon.) 

But Fire Island is not a typical barrier island, and its 
story doesn't quite conform to the pattern. The island 
began its development perhaps 3,000 years ago as the 
sea carved away at the headlands between Montauk 
and Southampton. Sand carried by the longshore cur- 
rents (see diagram) built up a spit that grew westward 
at an average rate of some 25 meters per year. Wind 
and waves built the spit higher and wider, forming the 
dunes and the "sand apron" behind them. 


In those 30 or so centuries, the sand spit has grown to 
a total length of about 80 kilometers; but its average 
width has never exceeded 300 meters. Sometime in 


longshore drift 

direction of waves 




The Origins of Fire Island 

Long Island is a part of an outwash 
plain that remains above sea level, 
which today is about 100 meters higher 
than it was during the Pleistocene. Long 
Island Sound is an inundated part of 
that outwash plain. Fire Island and other 
barrier beaches are made up of sand 
eroded by the waves from the post- 
glacial shores and carried southwest- 
ward by longshore drift. 

Southwestward migration of the spit that 
is now Fire Island. 

years ago 

recent centuries storms breached the spit at two points, 
and the section farthest west is now Fire Island, which 
is separated from the middle section by Moriches Inlet. 
It is still a child of its "mainland," getting its growth 
from sand eroded from the Montauk-Southampton 
shore. Fire Island today is a little more than 50 kilo- 
meters long. 


As the diagram shows, Fire Island is not only growing 
longer year by year; it is moving toward the mainland. 
This migration occurs because wind, waves, and cur- 
rents are removing more sand from the ocean side of 
the island than is being deposited there. Much of the 
sand is piled up on the beach by wind, tide, and waves 
and is blown landward, extending the sand apron and 
the marshland and encroaching on Great South Bay. 
Some sand is carried into the lagoon through Moriches 
and Fire Island inlets, and this helps to extend the 
marshland, build islands, and fill in the lagoon. It is 
entirely possible that this landward migration will con- 
tinue until Fire Island becomes a part of Long Island. 
Perhaps ocean waves will then build up new sand bars 
that with the help of the wind will develop into new 
barrier islands occupying almost the same locations as 
do the present chain of islands. But none of these 
developments will come to pass in your lifetime. 

1 K?t 


How to Be a Beachcomber 


The sprightly shore bird you saw playing tag with the 
waves on your early evening walk from the bay is the 
beachcombing champion of Fire Island, the sanderling. 
It is well named, because it likes sand beaches, and 
because its coloration blends well with the beach sand. 
But it could just as aptly have been named "wander- 
ling," for it is a champion globetrotter, too, known to 
lands around the Earth from the Arctic almost to the 
Antarctic. A sanderling that summers on the northern 
shore of Greenland may fly in winter to the south coast 
of Australia. And it's not even as large as a robin. 

You can see these birds from fall through spring and 
sometimes in summer; and you can learn from them 
some valuable lessons in beachcombing. Observe care- 
fully as they forage for food. Watch a sanderling dash 
on slender legs up and down the beach slope with the 
advancing and retreating waves at its heels. When a 
wave seems about to overtake it, the little shore bird 
may just flutter above the beach for a moment, then 
alight and follow the receding wave back downslope. 
This game of tag is actually a most efficient way of get- 
ting food, for small organisms living in the sand are 
closest to the surface when it is being washed by in- 
coming and receding waves; and the waves deposit 
other organisms carried in from the offshore waters. 









Notice that as the sanderling's twinkling legs carry it 
over the wet surface, it makes repeated downward 
thrusts of its awl-like bill. If you were able to examine 
this operation closely, you'd find that, probing the sand 
with slightly opened bill, it is extracting tiny animals — 
shrimp and other crustaceans, marine worms, mollusks, 
and invertebrate larvae. 

So here's your first lesson: look along the water's edge 
for small animals. But they are not usually abundant in 
this severe environment, and you'll need a magnifying 
glass — 10-power or more. And unless you're as nimble 
as a sanderling, plan on getting wet feet. 

Your Beachcombing Kit 

At little expense, you can make up a kit of handy beach- 
study aids that can be carried in a plastic shopping bag. 
Some useful items are 10-power magnifying glass, ther- 
mometer, binoculars, wide-mouth glass jar or clear plastic 
container, magnet, sieve or sifting box, trowel, metric 
ruler, and collecting bag. You may want field guides for 
bird or shell identification. A camera (with close-up lens) 
is a good record-keeping tool and a means of "collecting" 
specimens of living animals that you're not allowed to 
remove from the beach. And don't forget notebook and 

These chains of papery, hollow discs 
found on ocean and tidewater beaches 
are the empty egg capsules of large, 
carnivorous marine snails called whelks. 
As many as 200 eggs are enclosed in 
each capsule. 


There are certain clues that will help you find life in the 
sand. Most of the small holes you see are "percolation 
holes" made by air escaping from the sand; a few may 
be the entrances of burrows. Footprints indicate where 
birds have been foraging. Look for smaller creatures 
living in the spaces between sand grains; for this you'll 
need a strong lens or even a microscope. Digging and 
sifting will bring forth such animals as razor clams, soft- 
shelled clams, and the burrowing amphipod, Haustorius, 
a relative of the beach hoppers that is more closely tied 
to the sea. 

Donax, the active little coquina, or bean clam, normally 
found on southern beaches, arrives at Fire Island as a 
larva carried in the Gulf Stream. It moves up- and 
downslope with the tides. When a wave reaches the 
point where it lies buried, Donax leaps out of the 
sand and rides up on the wash. When the wash recedes, 
it quickly anchors itself, upends, and digs in. 

Actually, most of the life of the intertidal zone consists 
of fish and plankton that come in with the tide. Few 
animals and fewer plants have adapted to existence in 
this unstable, abrasive, and difficult habitat. When the 
tide is out, the sand is hard-packed. When the surf is 
washing it, the sand is subjected to violent motion. As 

Beachcombers All: I 

Compare the feeding habits of ani- 
mal visitors to the ocean beach. 
Examine such questions as: 

Do you ever see terns feeding on 
the beach? 

Do such shore birds as sanderlings 
and sandpipers use the same tech- 
niques for getting food as do the 

Which birds depend on the waves 
to bring fresh food? 

you will discover if you visit the beach the day before 
and the day after a storm, it can change dramatically 
overnight. Where you saw a 100-meter-wide beach, 
there may remain only a 50-meter strip between the 
foredune and the sea. A storm may remove the entire 
population of an animal such as the mole crab, which 
might not recover for years. Even after a long spell of 
moderate weather, you will do well to find a half-dozen 
species of animals below the surface of the sand. 

But with the lack of variety of life forms in this environ- 
ment, those species that have adapted to its stresses 
occasionally reach enormous numbers. The sea brings 
an unlimited supply of food to this zone, and popula- 
tions can build up rapidly. 

What songbirds do you find visiting 
the beach, and what are they 

Can you explain why in the intertidal zone of Great 
South Bay you'll find a much greater variety of forms 
than you will find on this exposed ocean beach? 

What information can you get from 
tracking mammals on the beach? 

Which visitors are scavengers? 


Each kind of animal in the intertidal beach occupies a 
zone that is strictly limited by the physical conditions. 
For example, the mole crab's feeding techniques re- 
quire that it remain in a narrow zone that moves back 
and forth with the tide; the crab does not ascend as far 
as the upper intertidal zone. 


Anyone interested in seashore life should become ac- 
quainted with the group of small crustaceans called am- 
phipods. There are more than a thousand species, and all 
are flattened sideways, which makes them easy to dis- 
tinguish from other crustaceans. They range in size from 
near-microscopic to about 30 millimeters long. Because of 
their abundance and because many animals eat them, 
they are important ecologically. 

The sand hoppers of the ocean beach are gilled air 
breathers. Their three hind pairs of abdominal feet are 
adapted for jumping, and the three front pairs for swim- 
ming. As though these animals were on the evolutionary 
road from a marine habitat to a dry-land existence, the 
jumping feet are much the larger. But the usual route from 
sea to land is not direct; rather, it is via estuaries and fresh 
water. No crustaceans, moreover, have entirely adapted 
to dry-land existence — not even the sowbugs you find 
under boards in your back yard. 


Apparently the small amount of moisture under the drift- 
wood and seaweed is enough for the upper-beach am- 
phipods. They feed upon the seaweed and upon dead 
animals, and in turn are fed upon by a host of predators: 
sandpipers, sanderlings, insects, centipedes, and many 

At the shore on the bay side of the island, you'll find other 
amphipods, as well as the distantly related isopods, which 
are flattened from top to bottom. 

Amphipods can 
swim, walk, or 
jump, and would 
be inconspicuous 
except for their 





Mole Crabs 

At low tide, stand barefoot on the part of the beach being 
washed by the waves. As each wave recedes, watch the 
sand where the water is flowing down the slope of the 
beach. If you're sharp-eyed, you may see a pair of tiny, 
featherlike objects project from the sand only to disap- 
pear when an incoming wave washes up the slope. Dig 
quickly into the sand where you saw the "feathers;" with 
luck you'll find a small, smooth, egg-shaped animal. This 
is the mole crab, which buries itself head up just beneath 
the surface of the sand in the lower part of the intertidal 
zone. When the waves are receding — not advancing — it 
extends its plumelike antennae to strain food particles 
from the water. As the tide ebbs and flows the mole crabs, 
which can swim, move with it so as to remain in the feed- 
ing zone. The females, as much as 40 millimeters long, 
may be too big for the sanderling to swallow; but the much 
smaller males are probably taken by this bird. 


The best tool for turning up large scoops of the sand is a 
small spade, like the folding entrenching tool sold in sur- 
plus stores. You'll have to work fast, for the mole crab is 
an amazingly adept burrower. One of its predators, the 
swimming crab, has developed an efficient means of cap- 
ture: it shoves its large claw downward into a bed of sand 
crabs. If it manages to grab one, it begins running in a 
circle, all the time holding onto its victim. The twisting 
motion enables it to pull the sand crab out of the tightly 
packed sand much as you'd pull the cork out of a bottle 
of wine. 

If you get one, put your specimen into a wide jar filled with 
sea water and with about 50 millimeters depth of sand in 
the bottom. Then drop the mole crab into the jar. It will 
burrow into the sand so quickly you'll miss it if you blink! 
This ability, an adaptation to life at the edge of the ocean, 
is due partly to its streamlined shape. Examine the crab 


with a magnifying glass; you'll see the several pairs of 
short, stout legs that enable it to dig in backwards. Study 
the branched breathing antennae, the feathery feeding 
antennae, and the eyes on very long movable stalks. 

To learn more about this remarkable crustacean's adapta- 
tions, life history, and behavior, read The Life of the 

* •-#• 

— «. -■- * 

Razor Clams 

The razor clam, so named because it is shaped like an 
old-fashioned straight razor, shares the mole crab's 
reputation as a fast burrower. But it lives in quieter sandy 
intertidal areas, where there is not the active surf so nec- 
essary to the mole crab's existence. Like the mole crab it 
cannot burrow in dry sand; but in the watery lower inter- 
tidal habitat it is a wizard at the disappearing act. 



t •••••• ■< 

W?fr. it- ■'■ 



The razor clam, which may reach 25 centimeters in length, 
occupies a vertical hole without any sand piled around the 
opening. It feeds when its burrow is covered with water, 
with part of its shell sticking above the surface of the sand. 
When the tide is out, you may be able to dig up a razor 
clam — but you'll have to move fast, for it has a muscular 
"foot" that enables it to descend quickly beyond your 
reach. Try to get it with the first fast spadeful of sand; if 
you miss, you might as well move on to another clam hole. 







. - i'.rt 



Like the sanderling, you shouldn't limit your beach- 
combing to the intertidal zone. You'll find the pickings 
less slim and the foraging easier on the upper beach. 
This is the zone between normal high-tide mark and the 
"toe" of the primary dune (see p. 46). It's good for sun- 
bathing and play, and also has lots of animal visitors. 
But when you consider the prevailing conditions — 
sands being shifted constantly in the wind and removed 
wholesale by storm waves; so much salt that the sur- 
face of the sand is often crusty with it; a lack of organic 
matter to provide food for burrowing animals; and ex- 
tremely dry conditions near the surface — you can under- 
stand why few animals are permanent residents. If 
you've walked barefoot across the upper beach on a 
midsummer day, you can also understand why animal 
visitors might be scarce at midday. 

On the upper beach as in the intertidal zone, the sand- 
erling's favored food is crustaceans. These include 
sand hoppers ("beach fleas"), abundant animals hardly 
more than a centimeter long that hide in vertical bur- 
rows in damp sand or live under the windrows of drift- 
wood, fish remains, shells, dead seaweed, and other 
debris at high-tide mark. Kick over some of this "beach 
wrack" and watch the little crustaceans jump like the 
fleas for which they have been named. There are also 

Be a Scavenger: G, I, T 

Make a bulletin-board display, or a 
mobile sculpture, of things found on 
the beach. Try to have a specimen 
representing each of the major ani- 
mal groups of the marine ecosys- 
tem — a fish skull, a horseshoe-crab 
shell, bird feathers, and a mollusc 
shell — as well as driftwood, dried 
seaweed, and other plant material. 

predatory and scavenging beetles, and flies and (on 
dead fish or birds) fly maggots. Together with gulls and 
visiting scavengers from the island's interior, these are 
nature's garbage collectors for the beach community, 
keeping dead plants and animal carcasses from piling 
up. (The gulls are also efficient removers of picnic 
scraps, and prey upon horseshoe-crabs and other live 
animals cast up by the waves.) Carnivorous centipedes 
and herbivorous millipedes are also found here. 

You can learn much about the beach community and 
the life of the sea by combing this zone for skeletons, 
shells, egg cases, and other animal remains. At high- 
tide mark and in the storm-wave zone look for the 
shells or dead bodies of horseshoe-crabs, which live in 
the ocean as well as the bay; for those necklace-like 
chains of whelk egg cases that mystify many a visitor to 
the beach; and for fish skeletons, which are more varied 
than you'd guess. Some of your discoveries will have a 
tragic note; too often, today, the beachcomber finds a 
sea bird, its feathers soaked with heavy, black oil, cast 
dead or dying upon the shore. 


If you keep a record of where you discover each living 
thing-above high-tide mark; in the intertidal zone; in 
the sand being washed by the waves; above or below 

Want to enjoy wildlife-watching the year 
around? Learn to identify gulls, terns, 
and shorebirds, the most conspicuous 
animals of the seashore. Observe their 
feeding behavior, plumage patterns, 
manner of flight, and calls. The sand- 
pipers, including the sanderling, are a 
big family that will require a lot of prac- 
tice on your part. A bird guide and 
binoculars are essential. The bird in the 
picture is a herring gull. 

the surface-you'll gradually piece together an ecologi- 
cal jigsaw puzzle: the pattern of life communities and 
the habitat requirements of different species. You'll 
observe that some animals, such as the sanderling, are 
not restricted to a single community or habitat. Others, 
such as the mole crab, because of their food require- 
ments and special adaptations to the environment, are 
never found beyond their special narrow zone, except 
by accident. Each of the life forms of the ocean beach 
has developed structural adaptations and behavior 
patterns that enable it to cope with physical hazards, 
find food, and protect itself from its enemies. It is this 
great variety of life styles that makes even this austere 
environment — almost a desert when compared with the 
rich bay community — an interesting place to explore. 

As your observations and examinations accumulate, 
you will begin to see emerging a pattern of seashore 
life — a structure much like that of a human community, 
in which each organism has a function, or "niche" in 
the ecosystem. 


After the Storm 

The most productive time for beach exploration is the day 
after a storm; the bigger the blow the better the beach- 
combing. But stay well above the dangerous surf that per- 
sists after the wind abates. Probe the windrows of jetsam, 
driftwood, and dead plants for animals cast up by the 
storm waves. You will find the valves of many molluscs, 
including such forms as the sea butterfly, knobbed whelk, 
shark' s-eye, transverse ark, jingle shell, and false angel 
wing; dead sand sharks and sea robins; and perhaps liv- 
ing specimens of surf clam, starfish, blue mussel, large 
hermit-crab, Tubularia and other hydroids, bryozoans, 
and sponges. 


4» '<«*( 




Up and Down in the Dune 
and Swale Zone 


The zone behind the beach is in some ways the most 
severe environment of Fire Island. It is very close to a 
desert in its physical characteristics; and the plants and 
animals that are able to thrive here have adaptations 
similar to those of desert species. Every living thing in 
the dune-and-swale community is modified in its habits, 
structure, and life history to cope with heat and dry- 
ness. And any part of this zone is subjected to heavy 
doses of salt spray, in varying degrees depending on 
whether it is on a windward (ocean) or leeward slope 
and on how far it is from the ocean. Thus, only plants 
tolerant of salt can succeed here. 

It is true that the dune-and-swale zone gets as much 
rain as the other island communities. But the porous 
nature of the sand allows rainfall to percolate rapidly 
down beyond the reach of ordinary plant root systems. 
This means that plants either must produce a root sys- 
tem that reaches to unusual depths or must have spe- 
cial adaptations to conserve what moisture they can 
capture during the rains. Animals either must go out- 
side the zone for water or must have the capacity to 
survive on moisture obtained from food. 

Let's explore this community by starting at the "toe" of 
the foredune — the upper edge of the beach. Here, even 

Beach grass, Ammophila breviligulata, a 
most important plant ecologically, is 
found on the coast from Newfoundland 
southward and on sandy shores of the 
Great Lakes. It spreads mainly by send- 
ing up shoots from the joints of creeping 
rhizomes, or horizontal underground 

on the beach itself, you may see an intriguing plant 
with an intriguing name, "dusty miller." You'll know it 
because it looks as though it had been dusted with a 
white powder — much as an oldtime flour miller might 
be. Its floury appearance is due to a dense matting of 
white fibers that insulates the plant against light and 
heat and probably provides some barrier to evaporation 
of moisture. Obviously, a plant growing in such a loca- 
tion must be very tolerant of salt spray. 

Now let's go up the face of the foredune — via a board- 
walk or other designated crossing. Here the dominant 
plant is beachgrass (Ammophila breviligulata). This 
plant is so effective in stabilizing the dune with its 
spreading roots that it is often planted in dune-restora- 
tion work where human traffic has trampled the vegeta- 
tion or a heavy storm has caused damage. The preva- 
lence of beachgrass on the ocean side of the foredune 
suggests that, like dusty miller, it has great tolerance 
for salt spray. Patches of beach-plum and bayberry 
shrubs occur among the beachgrass. 


At the top of the dune another shrub, bearberry, ap- 
pears. As you go downslope, the shrubs become domi- 
nant and beachgrass diminishes. In the more open 
areas where there is much bare sand, woolly beach- 

"Lens Effect" 

In hollows (including the swale itself, 
which is a large hollow), the sloping 
sides reflect sunlight and radiate heat 
toward the center, raising temperatures 
to levels as high as 50° C. 



Artemisia Stelleriana is the scientific 
name of beach wormwood, popularly 
known as "dusty miller" — a name ap- 
plied to at least four other plants. Arte- 
misia is most conspicuous on the wind- 
ward side of the foredune, and a few 
plants even grow on the upper beach. 
It is too scattered to be of importance 
as a dune-holding plant. Like saltspray 
rose, it is an Asian plant that escaped 
from American gardens and spread 
along our Atlantic coast. 


heather and seaside goldenrod are common. Look 
closely at the beachheather; notice its heavy, scalelike 
leaves — an adaptation against water loss and heat. 

The dip between the primary dune and the secondary 
dune is called a swale. You'll find changes in the veg- 
etation here that reflect the changed conditions. Does 
it seem hotter here than it was at the top of the dune? 
Of course the swale is shielded from cooling sea 
breezes. But as shown in the diagram, there is a further 
reason: when the sun is high the slopes of a swale or 
hollow in the dunes act much like a lens or reflector to 
concentrate the sun's rays. So plants growing in the 
bottom of the swale have to contend with greater heat. 
On the other hand, being closer to the water table (see 
diagram), they may have less difficulty reaching mois- 
ture with their root systems. Animals, being mobile, 
cope by remaining in burrows or escaping to other 
parts of the zone during the hottest part of the day. 

And what animals can you expect to find in this com- 
munity? You found that the beach and intertidal zones, 
unlike most natural communities, were populated pri- 
marily by animal forms. The green plants that are the 
base of the food web in these communities are the 
algae and plankton plants of the sea. The living animals 

What's in a Name? 

Why do we use Latin names such as Ammophila brevili- 
gulata or Artemisia Stelleriana when it's so much simpler 
to call the former "beachgrass" or to use the more inter- 
esting name of "dusty miller" for the latter? For one thing, 
most of the 1,000,000-plus known species of animals and 
375,000 species of plants have no names other than the 
Latin binomials ("two names") given to them by the scien- 
tists who classified them. Secondly, "beachgrass," for 
example, would be used only by English-speaking people; 
its Latin name is universal. Moreover, there are other 
species of grasses that can quite properly be called 
beachgrass — and some persons might refer to any grassy 
plant growing on the beach as "beachgrass." And to con- 
fuse matters further, there are other acceptable English 
names for beachgrass: sand-reed, psamma, dunegrass, 
and marram. One name might be used in one locality, 
another in the next county. Ammophila breviligulata, on 
the other hand, refers to one species, or kind, of plant, 
wherever it grows. Another "beachgrass," Ammophila 


arenarja, belongs to the same genus (plural: genera), or 
closely related group of species, Ammophila. Their differ- 
ent specific names, breviligulata and arenaria, reflect the 
fact that the seeds of each will reproduce only that kind of 
plant. Ammophila breviligulata seeds will not produce 
Ammophila arenaria plants, and the pollen of one will not 
fertilize the ovary of the other. 

If you were to mention (t beachgrass" to a European scien- 
tist who did not speak your language he would not know 
what plant you meant. But Ammophila Is a genus with 
species on both sides of the Atlantic, and the Latin name 
of each would not only be spelled the same everywhere, 
but would have basically the same pronunciation. 

The generic name is always capitalized. The specific 
name is not — except when it applies to a plant named for 
a person. (Artemisia Stelleriana was named in honor of the 
great 18th-century German explorer-naturalist Georg 
W. Stel/er.) 


* * 



* * ^ * 

^ * ** 



* ** * 

of beach and intertidal zones depend mostly on food 
brought in by the waves. But here in the dune-and- 
swale the situation is normal — a variety of rooted green 
plants is the food base. In crossing this zone, you will 
see as many as two dozen plant species. 

Except for birds that visit the dunes to feed on berries, 
there are few vertebrates here. The white-tailed deer, 
which roams over all the island, is a visitor to the 

Beach-heath (Hud- 
sonia tomentosa) 
is not found on the 
windward face of 
the primary dune; 
but in the swale it 
is more prominent 
than beachgrass. 

4 * 




**, * 






^ ^ 

/n the picture, the tracks of a fox merge 
with those of shore birds. Is there a 
story here? 



swale. This leaves only the cottontail and meadow vole, 
and sometimes the red fox, to represent the mammals 
as regular residents. You may see cottontails nibbling 
on the beach plums and other shrubby plants on cooler 
days or when the sun is low. But the voles come out of 
their burrows only at night. 

If you visit the dune-and-swale community in early 
morning, before the wind has had a chance to obscure 
all the signs of activity, you will find the surface criss- 
crossed with tracks of many kinds of animals. It is often 
possible to identify the maker of a particular track; and 
you may be able to recreate an encounter between prey 
and predator by studying the signs in the sand. One 
peculiar, corkscrewlike trail belongs to one of Fire 
Island's two common snakes, the eastern hognose. If you 
happen to meet this reptile, you may be startled by its 
defensive maneuvers. Upon your approach, it will 
spread its neck as if in imitation of the cobra, open its 
mouth wide, and hiss menacingly. It may strike at you, 
too, but its strike will fall short. It is only bluffing; even 
if it did bite it would do you no harm. Stand your 
ground and see what happens. If its threatening actions 
don't drive you off, it may suddenly roll onto its back as 









if dead. If this happens, turn the snake right-side-up; it 
will immediately flop again onto its back! While these 
antics of the hognose have made it some friends among 
nature lovers, it has unfortunately been much perse- 
cuted by man. Many insist that it is poisonous and 
vicious, and upon encountering the "puff adder" their 
first reaction is to dispatch it with a rock or stick. At 
the National Seashore, however, it is protected by law. 

The hognose snake is highly specialized in its diet; as 
in other parts of its range, it lives primarily on toads 
here. The only toad on Fire Island — the only amphibian, 
in fact — is Fowler's toad. Like the hognose snake, this 
toad has become adapted to life on the dunes; it is 
inactive during the hottest hours of the day, keeping 
cool and moist by burying itself in the sand. (In cooler 
habitats that provide shade, this would not be true.) It 
feeds on a variety of insects, which it captures with its 
sticky tongue. 

The invertebrates, or animals without backbones, 
include 97 percent of all the world's known animal spe- 
cies, but they are represented here by relatively few 
classes. No earthworms or other animals with moist 
skins can tolerate the hot, dry sands. Insects are the 
dominant group of invertebrates here as in other land 

The hognose snake, Heterodon platy- 
rhinos, inhabits sandy areas throughout 
eastern United States except in Maine. 
On Fire Island its chief prey is Fowler's 
toad, Bufo woodhousei fowleri. Unlike 
frogs, toads generally have dry, warty 
skins and hop rather than leap. They are 
not as much bound to water as most 
frogs, but return to water to breed and 
occasionally to soak. Fowler's toad is a 
late breeder, laying eggs until mid- 

Sunlight and Sand: I 

During early afternoon make a se- 
ries of temperature readings at a 
spot on the foredune or secondary 
dune that is fully exposed to sun- 
light. Read the temperature one 
meter above the sand (be careful to 
shade your thermometer from the 
sun to be sure of getting the air 
temperature); 5 centimeters above 
the sand; just under the surface of 
the sand; and 5 and 15 centimeters 
under the surface. How does this 
relate to the egg-laying behavior of 
the bembecid, or digger wasp, and 
to the daily schedule of activity of 
the Fowler's toad? 

environments. Special structural adaptations or be- 
havior patterns enable many of them to survive in desert- 
like conditions. Some beetles move up and down the 
plant stems, varying their distance from the hot sand as 
its temperature changes. Some insects burrow under- 
neath by day and come out at night. Some are light- 
colored, like many desert species, and absorb the heat 
of the sun less readily than do darker animals. 

Successfully coping with the heat and dryness of the 
dune environment are the abundant ants of various 
kinds. Dune ants are burrowers; some have special 
sand-carrying apparatuses on their heads that make it 
easier for them to dig deep into the sand to a level 
where it is cool and humid. The ants avoid activity on 
the surface during the hot part of the day. 

Mammals are less conspicuous than birds on Fire 
Island, but if you keep your eyes sharp you're sure to 
see the cottontail. Take a walk at daybreak; the red 
foxes are particularly active then. Watch for a fox den in 
the side of a dune. In spring you may see several cubs 
playing about the entrance. Without these predators, 
the plant-eating cottontails might become so abundant 
as to cause severe damage to the environment. 

Natural Communities 

A community in nature can be defined as the living part of 
an ecosystem — that is, the association of plants and ani- 
mals living in a particular physical habitat. An example: 
all the organisms in a pond, including, at particular times 
of the day or during particular seasons, those visiting it 
from other habitats. Plants growing around the edge 
because of conditions of moisture deriving from the pond 
might be considered part of the pond community; or, if a 
large area adjacent to the pond is vegetated by cattails 
and other rooted emergent plants, it would be called a 
marsh community. The two may overlap, and many animal 
forms might belong to both. (Such a transition zone is 
called an ecotone.) Study of the living things in any habitat 
will soon convince you that all are interrelated and inter- 
dependent, through such factors as competition, (for living 
space, food, etc.), predation, parasitism, commensalism, 
and habitat modification (as in the building of beaver 


A community need not be as large as a forest or a lake. 
It can be as small as a decaying log or stump with its 
myriad of organisms including mosses, fungi, bacteria, 
insect larvae, burrowing beetles, ants, etc. The log itself 
can be referred to as a "microhabitat." If you have a 
"balanced" aquarium — one that needs addition of neither 
food nor oxygen to keep it functioning — this is a micro- 
habitat with a living community. (What is the source of 
energy for the balanced-aquarium community?) 

A natural community, when you think about it, is compara- 
ble to a human community, in which an association of 
living things (man, pets, livestock, trees and other plants, 
pests, and wild animals) are living together in a physical 
habitat altered or largely created by man. Just think of the 
many ways in which all the plant and animal inhabitants of 
the human community are interdependent and interre- 
lated, and it will be easy to draw parallels with the natural 


Distance from ocean 

Cross-section of Fire Island 

220 meters 

dune and swale 




beach plum beachgrass 







hognose snake 


Fowler's toad 






*— ■ 


220 Distance from ocean 


Maritime Forest 




wild grape 




sassafras juneberry 


430 meters 


Great South Bay 

Food Chains 

The sun provides the energy by which green plants con- 
vert raw materials (water, carbon dioxide, and minerals) 
into living matter. Plant eaters in turn convert the carbo- 
hydrates and proteins of vegetation into animal tissue. 
Predators, relying on animals tor their food, are just as 
dependent on the green plants as are animals that eat 
green plants directly. In the dune-and-swale community, 
we can illustrate this flow of energy with a simple food- 
chain diagram: 

beach plum 

cottontail ► red fox 

Each arrow indicates the direction of the flow of energy 
from an organism to the organism that eats it. The food 



. , 8S8' 'S ; 

•V 1 ! 


chain ends with an animal that is not normally preyed 
upon. (There are no predators on the red foxes of Fire 
Island.) At each level of the food chain, about 90 percent 
of the energy is lost. It requires at least 10 kilos of beach- 
plum food to produce one kilo of cottontail, and that kilo 
of cottontail will produce only 1/10 kilo of red fox. Some- 
times the red fox eats the fruit of the beach plum, and then 
we have a shorter food chain and a more direct process 
for converting plant food into fox flesh: 

beach plum ► red fox 

A food web, made up of many interlinking food chains, 
is shown in the chapter on the salt-marsh community. 


I," w*§kW> i 




- **r1 

• _> V. 


szP : j 





^ : : x -A, 

.■ ' 


tv % 

*** = 

Mysteries of 

the Maritime Forest 

How did this strange woodland with the peculiarly 
cropped appearance come about? It looks as though a 
giant with a hedge clipper had tried to level it off even 
with the dune crest. And from your viewpoint on the top 
of the secondary dune the roof of the forest seems as 
dense as a hedge. The trees appear to be filling a great 
hollow, but this is somewhat deceptive. As you walk 
through the forest toward the bay, you will be gradually 
descending, with some ups and downs, to near sea 
level, where the northern edge of the forest borders the 
salt marsh. You will discover that the trees do not fill a 
deep hollow at all, and that the tallest of them does 
not exceed 8 or 10 meters in height. 

Now let's return to the crest of the secondary dune. If 
the wind, which is almost always present, is coming 
from the ocean, notice that it is strongest at this point. 
It is somewhat more gentle as you move down to the 
beach; and going in the other direction — into the 
forest — it diminishes almost entirely. 

If this is a particularly windy day you may be able to 
feel some of the salt spray that the wind has picked up 
from the crests of the waves. This salt-laden wind is the 
clue to the trimmed-hedge appearance of the forest. It 


Osmosis: G, I 

Devise an experiment to demon- 
strate the process by which salt 
removes the water from leaves. (A 
science teacher can help.) This in- 
teraction is the reason the maritime 
forest trees do not grow to their 
"normal" height and the reason that 
plants intolerant of salt spray can- 
not grow at all in the dune-and- 
swale community. 

does not really have a shearing action, like a hedge- 
clipper, though the effect is the same. 

All the plants in the dune-and swale community are of 
necessity tolerant of salt, for they are directly exposed 
to the salty ocean breezes. And what happens when the 
wind sweeps over the secondary dune? Salt is deposited 
on the highest branches and leaves of the forest trees. 
These are much less tolerant of salt than the dune-and- 
swale plants, and the new buds and leaves at the top 
are killed. So the forest cannot grow higher than the 
secondary dune, and once they have reached the crit- 
ical level the trees can grow sideways only. The spread- 
ing branches at the top thus form a dense canopy that 
from the dune crest looks almost solid enough to walk 
on. The vegetation below this dense cover is affected 
little by the salt-laden wind; but as you can see it is de- 
prived of most of the sunlight that falls on the forest. So 
only plants that are tolerant of shade can survive in the 
understory and on the forest floor. You will not find any 
beach grass here, though a few of the sun-loving pines 
grow in the edges of the forest on the secondary dune 
and near the marsh. 


Most of the trees 
of the maritime 
forest can be iden- 
tified from the 
shapes of their 
leaves. Shown are 

(1) juneberry, 

(2) sassafras, and 

(3) holly. 

In Fire Island's largest stand of maritime forest, three 
species of trees are clearly dominant. An examination 
of the canopy will show that it is made up mostly of 
American holly, sassafras, and juneberry. Where condi- 
tions vary, you'll find other species. In boggy places 
there are sour-gums (swamp tupelo) and swamp azalea 
(a tall shrub rather than a tree). There are scattered 
black cherries, and here and there a big oak (big for 
the maritime forest, that is). Only where an opening in 
the canopy admits enough sunlight can you find a 
pitch pine. 

It won't take you long to learn all the tree species in this 
forest. And since the vegetation of the forest floor is not 
greatly diverse, you should be able to identify the com- 
mon shrubs and herbaceous plants with a little work. 
Why do you think so few species grow here? It is not 
entirely a matter of available sunlight; consider also 
such factors as the sandy soil and the salt that rain- 
storms wash from the uppermost foliage onto the forest 


Detailed studies of the plantlife in the maritime forest 
at Sailors Haven have enabled scientists to trace the 
history of this unique community quite accurately. Care- 
ful observation will enable you to discover some of the 

Profiling a Community: I, G 

Stake out a 10-meter-square plot of 
maritime forest (get permission from 
the ranger) or a narrow strip of the 
forest or thicket bordering the 
boardwalk, and make a profile 
diagram of the habitat. Be sure to 
include any birds, insects, and 
other animals you observe. The 
generalized maritime forest dia- 
gram on p. 60 can serve as a guide. 
To get a greater variety of plant 
species, you might pick a plot that 
includes a boggy spot or a forest 

clues yourself. Notice, for example, that the dominant 
forest trees — holly, sassafras, juneberry — are vigor- 
ous and healthy. There are very few dead specimens of 
these trees. On the other hand, there are a number of 
dead oaks, redcedars, and pitch pines — some standing 
and some on the ground — but very few living speci- 
mens. This suggests that the forest has undergone a 
fairly recent change; that the pines, oaks, and red- 
cedars are on the way out; and that the holly, juneberry, 
and sassafras are here to stay. 

If climatic changes, severe storms, or other events do 
not occur to upset the present balance, the forest may 
remain for the foreseeable future in its present state. 
We call such a stabilized forest a "climax community." 
Climax communities come about through a process of 
natural succession, which may require a hundred or a 
thousand years to run its course. In the case of the 
maritime forest here, it appears to have required about 
250 years. But barrier islands, creations of the winds 
and currents, are subject to sudden drastic alteration, 
or even destruction, by these same forces. So the con- 
cept of a climax community doesn't mean quite the 
same here as it would in a mountain forest — where 
even a fire or an unusually violent storm generally does 


no more than cause a setback to an earlier stage in 
succession. One winter storm could cut Fire Island in 
half at this point, eliminating the forest. Also, the migra- 
tion of the barrier island toward the mainland might re- 
move the habitat. At Assateague Island National Sea- 
shore in Maryland and Virginia, cedar stumps on the 
beach mark the location of a former swamp. 

Sometime between 200 and 300 years ago the site of 
this forest was an area of bare, windblown sand. But it 
was not to remain barren for long. It was soon invaded 
by the seeds of pioneering dune plants. First, while 
sand was still being deposited on the dunes, came 
beach grass. This is the same plant now dominant on 
the windward side of the primary dune. In spots where 
the wind was removing sand, it was probably woolly 
beachheather and seaside goldenrod that first gained a 
foothold. Woolly beachheather not only pioneered, but 
helped stabilize the habitat by trapping blowing sand. 
But how did these pioneering plants get the nourish- 
ment all living things need for growth and reproduc- 
tion? There are virtually no nutrients to be derived from 
sea sands; so they had to get their food from the air — 
minerals borne on the winds both from sea and from 
land. As the plant communities developed, they added 


Comparing Communities: A, I, 7 

Make a comparative study of the 
maritime forest and a high thicket 
community. Chart the species of 
woody plants and their heights, 
height of protective dune, distance 
from ocean, and species of herb- 
aceous plants and birds and other 
animals. If you have a camera you 
can take pictures to show differ- 
ences and similarities. If you can 
draw even a little bit, make profile 
diagrams of the two habitats. It is 
best for comparative purposes if 
you choose two locations at ap- 
proximately the same distance from 
the ocean. This will eliminate dis- 
tance from the ocean as a cause of 
differences you discover between 
the two forests. Because of the 
prevalence of poison-ivy in the 
thicket, you should make most of 
your observations at the edge, or 
along established trails and board- 

organic material to the sand, and gradually an environ- 
ment was created that enabled increasingly diverse 
plant associations to grow. 

As the pioneer plants spread over the dunes, they cre- 
ated conditions favorable to such plants as bearberry, 
bayberry, poison-ivy, Virginia creeper, and beach-plum. 
In the more stable places, pitch pine and redcedar were 
able to get a foothold. These woody plants — shrubs, 
vines, and small trees — then created an environment 
that permitted the development of still another plant 
community, which was dominated by blackcherry, post 
oak and other oaks, and highbush blueberry, and by 
pitch pines and redcedars persisting from the previous 
community. The other early plants, from beachgrass to 
beach-plum, had by this time either disappeared or de- 
clined, because conditions were no longer favorable for 
them or because they could not successfully compete 
with the new plants for the available food, moisture, 
living space, and sunlight. 

This blackcherry-oak-blueberry-redcedar-pitchpine 
community has by now been almost entirely replaced 
by the holly-sassafras-juneberry maritime forest. We 
can't pinpoint the time when this transition began, but 


some of the trees have been examined to determine 
their ages. A core taken from one American Holly shows 
that it began to grow about 1804, the year Lewis and 
Clark started their western expedition. The apparent 
stability of this forest suggests that it will remain for a 
long time to come, barring natural catastrophes or 
man's interference. 

The process of natural succession occurs because 
a plant community creates conditions that favor other 
species at its own expense; thus each community is 
replaced by another until a climax community — one that 
does not in this manner seal its own doom — is estab- 
lished. The fascinating thing about succession at Fire 
Island is that you can retrace it, in a sense, by walking 
from the beach to the maritime forest; you move from 
bare sand through a beachgrass-dominated zone to the 
shrubs of the swale to the forest hiding behind the pro- 
tective secondary dune. You can find all the plants 
mentioned above, if not in clearly demarked communi- 
ties at least roughly in the same order of occurrence as 
the order in which they became established in the suc- 
cession cycle. 


It is not only plants that follow a successional pattern. 
As you pass through the various zones from beach to 

ocean winds 

7.5m height of secondary dune 

canopy \ 


black racer 
white-footed mouse 

The Maritime Forest 

Maritime forests typically develop 
through the process of natural succes- 
sion in areas first supporting such soft- 
stemmed plants as beachgrass or sea- 
oats, and usually have canopies de- 
formed by wind and salt spray. Like 
other plant communities, they have 
characteristic associations of animals. 
About 11 species of mammals and twice 
as many birds breed in the Fire Island 
forest; many others forage in it or pass 
through on migration. In earlier times 
it probably sheltered otter, gray fox, 
bobcat, and black bear, as well as the 
red fox and deer we see today. 

forest, make a note of what animals you see, and what 
plants they are feeding on or using for perches, shade, 
or other purposes. If you make such observations over 
a long enough period of time, you should be able to de- 
velop a distribution pattern that will roughly parallel the 
changes that took place in the animal populations dur- 
ing the succession from bare sand to maritime forest. 

You will learn more about the concept of natural suc- 
cession in plant-and-animal communities in the chapter 
on salt marshes. 


An ecosystem is a plant-and-animal community and its 
physical environment. For example, when we speak of the 
salt marsh ecosystem we mean, along with the living 
sedges, grasses, algae, and other plants, the mud or sand 
in which they are rooted, the invertebrate and vertebrate 
animal life, the dead plant and animal material, and the 
water, minerals, atmosphere, and incoming solar energy. 

The salt marsh can be considered part of a larger eco- 
system, the estuary; on the other hand, two well defined 
zones of the salt marsh ecosystem with distinctly different 
plant associations can be treated as separate ecosystems. 

When you encounter any new word beginning with "eco-", 
keep in mind that it is taken from the Greek word eko, 
meaning "home." Ecology is the science of the home 
(-logy = science) — that is, the study of the relationships 
between the living things in an environment. 



Wet Your Feet in the 
Salt Marsh 


At low tide, walk out onto one of the expanses of flat 
terrain on the island's north shore between low- and 
high-tide marks. If you're in a zone that is covered and 
uncovered by each day's tides, you're probably in the 
salt-marsh cordgrass community. In thousands of hec- 
tares of our coastal wetlands, cordgrass is the only 
rooted plant growing. It thrives best in soil that is in- 
undated about half the time. Along tidal creeks, it may 
be as tall as a man. 

This is probably the most rewarding of Fire Island's life 
communities for the wildlife watcher. And don't make 
the mistake of thinking that the animal life consists of 
the ducks, shore birds, and wading birds that fly off at 
your approach. Look down as well as up — and look 
carefully. If you're not making too much disturbance, 
you may spot the fiddler, an important citizen of the wet 
marsh. It's only a crab — and a small one at that. But this 
crab looks as though its growth hormones have gone 
awry; it is waving an oversize foreclaw back and forth 
like a huge fiddle. As you approach, the crab will scurry 
toward one of the holes in the mud, apparently unhin- 
dered by the burden of the claw it carries before it. The 
fiddler may reach the entrance to a burrow, quite likely 
not its own, before you can catch it. But with patience 
you should get a specimen to examine. It won't harm 

The fiddler crab, 
Uca pugnax, with 
a 25-millimeter- 
long shell, is Fire 
Island's smallest 
crab. The related 
Uca musica — a 
noisy creature — 
has a shell only 
8 mm long! 

you. Look at its other foreclaw — the normal-sized one. 
It is spoonlike and is used, logically enough, in feeding 
upon minute plants scraped from the mud. This comical 
little show-off is the male of the species; the female fid- 
dler has two spoon-claws, which suggests that she can 
feed more efficiently than the male. Perhaps this is a 
necessary difference, for she must produce the eggs 
that maintain the species. The male's big claw, used in 
mating and territorial displays, is useless for feeding. 

The fiddler crab and saltmarsh cordgrass are well 
adapted to a half-land, half-water existence. The crab 
can breathe quite well out of the water, so long as its 
gills remain moist. The cordgrass is one of the few 
flowering plants that will grow in the lower intertidal 
zone; another species, saltmeadow cordgrass, grows 
on the drier flats where only the highest tides reach. 
Low cordgrass marsh is the more productive; one 
hectare can produce 10 tons per year of green plant 
material, dry weight — more, in fact, than any other na- 
tural land community. This is a bountiful base not only 
for this zone but for the adjacent estuary that is en- 
riched by it. The saltmarsh cordgrass community is an 
ideal place to study Earth's natural rhythms and life 


What Good Is a Salt Marsh? 

This question reflects our historic indifference to and 
abuse of a priceless natural resource. Much of our exten- 
sive coastal marshland has been drained for farming or 
mosquito control; filled in for housing, industry, highways, 
and recreation; used as a handy place to dump refuse; 
and badly polluted by sewage and factory effluents. Yet 
the salt marsh is the most productive of all natural com- 
munities, exceeded only by fertilized sugar cane fields. 

The abundant growth of green marsh plants provides the 
base of a food pyramid unsurpassed in variety and rich- 
ness. The animals that feed on the marsh plants are in turn 
eaten by predatory animals. Besides the profusion of 
vertebrate and invertebrate animals that spend all or most 
of their life cycles in the tidal marsh, there are many 
marine species that use them as nurseries. 

Though you may not have realized it when eating seafood 
such as fish sticks and crab cakes, many of the animals 
that are important food for man are caught in the marsh. 

Many hatch and spend their early lives there, or live in 
estuarine or offshore waters on nutrients that flow from 
the rich marsh ecosystem. Marshes offer protective cover 
and abundant food for fishes, molluscs, and crustaceans. 

The marsh is also a valuable habitat for nonaquatic forms. 
Most of these are rodents, such as the meadow vole, that 
feed upon the vegetation, or predators that feed both on 
rodents and upon fish and other aquatic life. Eagles, 
ospreys, marsh hawks, owls, ducks and geese, shore 
birds, gulls and terns, rails, herons of many kinds, dia- 
mondback terrapins and snapping turtles, raccoons, mink 
. . .the list is almost endless. Not every one of them is 
found in the Fire Island marshland; but if you're a bird 
watcher or nature photographer you'll do well to spend 
some of your time in this habitat. 

The existence of much of our coastal lowland derives from 
salt marshes. The vegetation slows the movement of water 
and traps sediments, building up the land. It also helps 


prevent shoreline erosion by breaking the force of waves, 
currents, and wakes of vessels. 

The value of salt marshes for recreation is recognized by 
many, especially waterfowl hunters and wildlife watchers. 
As for educational and scientific benefits, marshes are 
excellent laboratories for ecological studies, and a knowl- 
edge of salt-marsh ecology is absolutely essential in 
marine fisheries research. 

The black-crowned 
night heron has 
a thicker neck, 
heavier body, and 
shorter legs than 
most of the heron- 
and-egret family; 
and its habits are 
somewhat noctur- 
nal. Look for it 
early and late in 
the day. 

Coastal marshland is called "wasteland" 
by many who, ignoring its value, wish to 
convert it to "useful" purposes. Yet a 
cordgrass marsh produces four times as 
much plant growth as a cornfield — with- 
out artificial fertilizer or cultivation! 







As cordgrass plants break up or die, fragments of de- 
caying plant material, called detritus, are washed by the 
receding tides into the bay, where they furnish food for 
amphipods, ostracods, isopods, polychaete worms, and 
other animals. These detritus feeders are eaten by small 
predators such as pipefish and sticklebacks; the small 
predators in turn are fed upon by flounders and other 
fish that provide food for man and larger predators. 

The marsh itself is rich in variety and abundance of 
animal life. Many burrowing animals feed on green 
plants — cordgrass and algae — or on fine particles of 
organic matter contained in the mud. These and all the 
other animals of the broad marsh-bay ecosystem are 
dependent upon a group of organisms we call decom- 
posers: the fungi and bacteria that begin the process of 
breaking down the cordgrass and other green plants, 
and the small crustaceans, worms of various types, and 
other invertebrates that feed on the detritus and convert 
it to animal protein that feeds the host of predators. 
Even direct feeders on green plants, such as the purple 
marsh and fiddler crabs, can be considered decom- 
posers, since their digestive processes only partially 
utilize the plant material, and their fecal pellets contain 
fine particles that become part of the detritus. 

Natural Succession 

The salt marsh is an excellent field for the study of the 
process by which one natural community replaces another 
and then creates conditions that bring about its own re- 
placement by a third community. It would require more 
than your own lifetime to follow the series of stages in the 
succession process that leads from an abandoned farm 
field to a mature broadleaf forest. But on Fire Island you 
can observe the creation of new land from the sea and can 
see the pattern of the successive stages that lead eventu- 
ally to thicket, maritime forest, or other relatively stable 
community. On the bay side of the barrier island, the first 
stage in the succession story is the creation of a new 
low-water marsh. 

Look for a place in an inlet or tidal creek where mud has 
built up above the low-tide mark and enabled a clump or 
two of salt-marsh cordgrass to take root. The underground 
stems of this plant spread rapidly, sending up new tufts of 
grass that trap more sediment and form an island, or build 


out from the existing marsh. As the tides deposit more silt 
and the dead grass stems and leaves accumulate along 
with windblown sand and shells and other remains of dead 
animals, the marsh becomes higher — and the tides cover 
it for fewer hours of the day. Eventually, after many years, 
a level beyond all but the highest tides is reached; by this 
time the saltmarsh cordgrass has been replaced by salt- 
meadow cordgrass, and we have a high-water marsh. The 
low-water marsh, by its own success, has eliminated the 
conditions that favored it and has thus paved the way for 
its replacement by a plant community adapted to the 
new conditions. 

Salicornia, or glasswort, which has become established in 
the later stages of the low-water cordgrass marsh, remains 
in the new marsh community, where along with black 
grass, three-square rush, and spike rush it mixes with the 
salt-meadow cordgrass. As the marsh builds up still 
higher, the cordgrass disappears, leaving a stand of the 


other three plants. These eventually give way to a border- 
line community between marsh and upland, such as 
Phragmites (reed) grassland. When the soil base has 
built up to the point where it is no longer affected by even 
the highest tides, it supports an upland community. This 
might be beachgrass grassland, low thicket, or any one of 
several other types, depending upon such factors as 
deposits of windblown sand and proximity of the water 
table to the soil surface. 

By walking from the bay across the marshland to the up- 
land, you can see the same succession of communities 
that has occurred in one locality over a long period of 
time. The pattern may not exactly parallel what has been 
described above; it will vary, depending upon what part of 
the barrier island you are exploring. 


On the mainland, natural succession generally proceeds 
until a community develops that does not create condi- 
tions leading to its replacement by another. This is called 
a climax community; it will prevail until fire, flood, other 
natural catastrophe, or the activities of man either elimi- 
nate the plant community or alter it so drastically as to set 
it back to an earlier stage of succession. On Fire Island, 
however, the dynamics of barrier-beach ecology are such 
that a climax community in the usual sense does not exist. 
The is/and itself is migrating toward the mainland as the 
ocean eats away at its south shore and new marshland 
builds up on the bay side. Perhaps the nearest thing to a 
climax community on the island is the holly-juneberry- 
sassafras Sunken Forest, which has developed from bare 
sand over a period of two centuries. 

For a fuller understanding of natural succession, refer to 
some of the books in the Reading List. 


► short-eared 






Food Web of the Salt Marsh 

Backyard Ecology: I, G, 7", Y 

The process of natural succession 
is so slow that the changes leading 
to a climax community may span 
several human lifetimes. But you 
can observe the early stages by 
watching a newly abandoned farm 
field, an empty lot, or a corner of 
your backyard or schoolyard 
allowed to return to nature. Record 
the changes in plant and animal life 
as one community creates condi- 
tions that enable another to replace 
it. During the first year the grass is 
not mowed, a piece of lawn will be 
converted to a patch of wildflowers. 
The increase in numbers and kinds 
of animals will be noticeable as the 
"weeds" grow high and shrubs and 
tree seedlings gain a foothold. Keep 
a photographic record of the suc- 
cession process for as many years 
as you can. 

The diagram of the saltmarsh food web shows how in- 
tricately all these animals are interrelated and how all 
are totally dependent upon the green plants and ulti- 
mately on the sun's energy. Because the saltmarsh 
provides much of the nutrient for the adjacent estuary, 
the diagram includes part of the Great South Bay 

Where there is no regular (daily) inundation by the tides, 
a different type of saltmarsh will develop. On Fire Island 
you will find several kinds of high, or dry, marsh. There 
are solid stands of Phragmites, the towering reed grass. 
This plant is utilized by so few organisms that it is al- 
most valueless as wildlife habitat. There are also ex- 
panses of saltmeadow cordgrass, in the zone flooded 
only by occasional tides. Saltmeadow cordgrass is not 
so productive as saltmarsh cordgrass. Here the fiddler 
crab is largely replaced by the purple marsh crab, 
though the zones of the two overlap and the latter, pri- 
marily a vegetarian, sometimes preys upon the smaller 
fiddler. Among shore birds, the greater yellowlegs is 
often seen fishing for minnows in the marsh waterways, 
while the lesser yellowlegs prefers the short-grass 
marshes where it hunts its food, mainly insects and 
small crustaceans, in wet places and shallow pools. 


The Peregrine, an Endangered Species 

Some of the birds and mammals once 
common on our barrier islands and in 
our offshore waters have been brought 
close to extinction by man's greed and 
carelessness. Destruction of habitats, 
environmental pollution, and ruthless 
hunting have all contributed to the de- 
cline of such species as the noble pere- 
grine falcon, which is perilously close 
to disappearing but can still occasion- 
ally be seen hunting rodents in the salt 
marshes and other coastal habitats. In 
the middle decades of this century the 
peregrine suffered enormous losses 
from such pesticides as DDT. Stricter 
environmental controls and better pro- 
tection may bring the population back 
to a level that will assure its survival. 

Knowledge of any animal's habits and familiarity with 
its preferred haunts will make wildlife finding more re- 
warding foryou. Keeping records of your observations — 
times, habitats, behavior, etc. — will enhance your ex- 
perience and build your skills. 

The wild animals of Fire Island do not always conform 
to the standard behavior of their species as described 
in the field books. For example, the muskrat, whose 
lodges dot coastal and inland marshes on the mainland, 
doesn't even seem to build a mound of vegetation 
as a home here. Instead, it digs burrows in the walls of 
mosquito-drainage ditches or in the sandy banks of 
small ponds. It will take some searching to get so much 
as a sight of this rodent. The muskrat ordinarily is 
preyed upon by many birds and mammals. But here it 
is probably not an important link in the saltmarsh food 
chain. Snapping turtles are not abundant. Still, the 
muskrat must be on guard against other regular ene- 
mies, such as red foxes and large hawks. If you're 
going muskrat-watching, be sure you know how to rec- 
ognize this rodent's tracks. Watch for them in muddy 
spots along the ditches and the edges of small ponds 
and cattail marshes. The records of wild mammals on 
Fire Island are quite sketchy. You can help fill the 
gaps — so report your observations to the park rangers. 



ftiMiiMir«m ' j^l' -JiSBjfer' 

* # 

^ -i-,-. 


• ■v. 


Who's Who in the Zostera 


You don't need a boat to get on close terms with the 
life community of Great South Bay. This shallow coastal 
lagoon, as much as 8 kilometers wide and many times 
as long, slopes so gradually from the shore that you can 
wade out hundreds of meters from the narrow beach. 
Simple collecting gear, most of which you can salvage 
or make yourself, will enable you to sample the fasci- 
nating array of living things. At the base of this com- 
munity is a plant called eelgrass. 

A freshwater plant, not at all related to Zostera, also 
goes by the name "eelgrass." To confuse the matter 
further, neither of these plants is a member of the grass 
family. The name that definitely distinguishes Fire Is- 
land's eelgrass from other plants is Zostera marina 
(pronounced zoss-TARE-uh ma-REE-na). 

You'll find Zostera growing thickly in much of the shal- 
low offshore water on the lagoon side of Fire Island. It 
grows in mud or soft sand bottoms, generally in brack- 
ish waters but also sometimes in highly saline areas. It 
is one of only a few flowering plants that have gone 
back to the sea from the land, where that branch of the 
plant kingdom evolved. Almost all of the green plants 
in the sea are nonflowering, and are loosely grouped 
under the term "algae." 

The Zostera Community 

Nereis virens 

coralline algae 

Nassarius obsoleta 

Membranipora monostachys 

Retusa canaliculata 

Hermit-crabs, the clowns of the eelgrass 
jungle, walk about with their snailshell 
homes on their backs, scavenging for 
bits of animal matter on the bottom. 
Shown on the facing page are a few of 
the animals and plants that live not on 
the floor of the eelgrass community but 
on the Zostera plants themselves. 

Examine Zostera closely. You'll see that it does indeed 
resemble grass, even to having jointed stems. With a 
hand lens you'll be able to see its tiny green flowers, 
which develop in grooves on a leaflike spike. Unlike 
algae, it has true leaves, which are ribbonlike and flex- 
ible and grow to a meter in length. The beds of Zostera 
are extensive, and most of the beach wrack on the 
shore of Great South Bay consists of dead leaves of this 

Why is this plain-looking saltwater weed so important? 
Certainly, few of the animals in this community eat 
it, though it is the staple diet of the American brant, 
a small goose that you may see in winter along this 
coast; and several ducks are known to eat small quan- 
tities of it. But look at the plant through your hand lens. 
Feel its texture. That slippery coating is a growth of 
algae — and it is on this that a great variety of organisms 
feed. Snails, including the centimeter-long Lacuna and 
the iridescent Margarita, are the most abundant of 
these algae feeders. 



Balanus balanoides 

Hippolyte zostericola 

Botrillus schlosseri 

Bittiam alternatum 

Molgula manhattensis 

Mitrella lunata Caprella 

Syngnathus fuscus 

Also found in enormous numbers on and amongst the 
Zostera plants is Nassa, a predaceous snail that feeds 
on other molluscs. Nassa itself is devoured by the 
hermit-crab, which adds insult to injury by taking its 
victim's shell as its home. Examine Zostera leaves for 
small, gelatinous masses of bright yellow eggs of Nassa. 
Your search may reveal another animal that you first 
take to be a snail but is actually a worm, Spirorbis. Its 
home is a minute, limy tube coiled in such a way as to 
resemble the shell of a snail, and cemented to one spot 
on the Zostera blade. It has even developed its own 
version of the operculum, the horny plate that serves to 
close the entrance to a snail's shell: in Spirorbis, one 
gill is modified to form an operculum that closes the 
end of its tube! 

Besides these and other tube worms and snails, inhab- 
itants of the Zostera beds include clams, small fishes, 
edible crabs, horseshoe-crabs, and smaller crusta- 
ceans. With a few sweeps of a fine-mesh net you should 
be able to capture many of these organisms. With luck 
you'll get a sea horse or its close relative the pipefish. 

a Elysia d snail (Lacuna vincia) 

b bryozoan, algae e snail eggs 
c Spirorbis f Didemmum 

The Eelgrass Microhabitat: I 
Examine some eelgrass plants 
(Zostera) with a hand lens and, if it is 
available, a low-power microscope. 
See how many kinds of organisms 
you can find and identify, using 
books listed in the Appendix. Don't 
overlook the roots. Do any of the 
organisms appear to be feeding on 
Zostera itself? Put your sample into 
a jar or larger container of bay 
water, and examine it at intervals to 
see if eggs hatch or other changes 
occur. Keep it out of the sun, to 
prevent warming and loss of oxy- 
gen. Replenish frequently with fresh 
sea water. These water changes 
may introduce new organisms into 
your sample. 

Put your living specimens into a container of bay water; 
a white basin is good because it makes seeing the 
smaller forms easier. Be sure to return all living animals 
to the bay; you won't be able to keep them alive out of 
their natural environment unless you have a well de- 
signed marine aquarium set up . 

Though they are part of the larger Great South Bay eco- 
system, the Zostera beds are in themselves a dynamic 
plant-and-animal community. You could easily spend a 
whole summer getting acquainted with the inhabitants 
of this shallow offshore zone. 

Let's see how a few of these animals fit into the Zostera 
community. We might start with one of the worms. The 
word "worm" is a bit of a problem, though, because 
many unrelated forms of animal life are called worms. 
Nereis virens, the clam worm, belongs to the phylum 
Annelida, which, with more than 6,000 species, is the 
best known of the "worm" phyla. It includes earth- 
worms, leeches, and the Tubifex worms you buy at the 
pet shop to feed your tropical fishes. 



Nereis virens (left) 
and detail draw- 
ings showing the 
head of Nereis 
with its pharynx 
retracted and ex- 

Nereis belongs to the class of segmented worms some- 
times called "paddle-footed annelids." During the day 
it burrows in the mud and sand; at night it emerges and 
swims about like an eel. It is a voracious predator, feed- 
ing on invertebrates, including other worms, and em- 
ploying an unusual device for capturing and eating its 
prey. Its two horny, notched jaws are well back inside 
its body. Suppose it comes upon a small crustacean 
such as the skeleton shrimp, only two centimeters long. 
The clam worm turns its pharynx inside out, everting 
it right through its mouth and bringing the jaws into 
position for action. Seizing the crustacean in its jaws, 
the worm pulls its pharynx back inside its body, where 
the jaws tear the shrimp to pieces. 

Predator though it is, the clam worm is not at the top 
of the food chain. When swimming about at night it 
often falls prey to fishes. In fact, large numbers of clam 
worms are dug from tidal flats to be sold to fishermen 
for use as bait. 

The Web of Life: G, /, A, T 

Individually or as a team, capture or 
observe and identify as many ani- 
mals of the Zostera community as 
you can. Draw a food web showing 
how each fits into the community — 
as predator, scavenger, browser, or 
filter feeder — and be sure to in- 
clude plankton and algae, as well 
as any birds you see feeding in the 
zone. You will need to use refer- 
ence works to determine the food 
habits of the animals. The food web 
can be constructed at home or 
school from your field notes. 

If you should capture a specimen of Nereis virens, use 
a bit of caution. You're in no danger from this 30- or 
40-centimeter-long worm; but those jaws can give you 
a painful nip. Unless you can seize it behind the head 
as experienced fishermen do, use a net to scoop it up. 

With your captive in a container of water, notice how it 
swims, snakelike, with the help of the paddle-like ap- 
pendages on each body segment. Notice its metallic 
iridescence and its sense organs — eyes, palps, ten- 
tacles, and cirri. 

Since the molluscs of the Zostera community include 
filter feeders, browsers on algae, and predators, we 
can't place them as a group in any level of the food 
chain. The hardshell clam is one of the most interesting 
to us, since it is a favorite food of man. If you can bor- 
row a clam rake, it shouldn't take you long to get a spe- 
cimen or two. You might even be able to excavate one 
with your toes as you wade in the shallows; for although 
the hardshell is a burrower, it usually remains just be- 
low the surface of the sand. It feeds by extending its 
siphon, or "neck" — which is actually a part of the pos- 
terior end of the clam's mantle. Through the siphon it 
draws water, using its gills as internal filtering devices 


V ; ^" 



.v. - / 



The oyster drill, which rarely reaches 
2.5 centimeters in length, bores neat 
round holes in the shells of its victims 
and sucks out the soft parts of their 
bodies. You will find shells on the beach 
that show that their owners perished in 
this way. Such shells with holes ready- 
drilled can be easily strung into neck- 

to extract any microscopic organisms (plankton) taken 
in with the water. Then the water, along with waste 
products, is discharged through the same opening. 
Many molluscs, including oysters, mussels, and scal- 
lops, and many other invertebrate animals of the bay 
are filter feeders-reflecting the importance of small 
plankton in the food web. 

The hardshell clam, like most organisms in the Zostera 
community, is itself food for other animals. Small clams 
are eaten by the abundant horseshoe-crabs, which bur- 
row under the surface of the sand in search of prey. 
The oyster drill, a carnivorous snail, is able to cut a 
hole through the shell of a clam and devour it. And the 
clam worm, true to its name, is a predator on the hard- 

All crustaceans breathe with gills and 
have two pairs of antennae. True crabs 
are crustaceans with a reduced abdo- 
men that is folded under the body and 
cannot be seen from above. The hermit- 
crab's abdomen is long — and it is invis- 
ible only because it is coiled into a snail 
shell. Also included in the Crustacea 
are barnacles, amphipods, isopods, 
copepods, shrimp, lobsters, crayfish, 
sowbugs, and water fleas. 

Crustaceans are well represented in the Zostera com- 
munity. The members of this class are so varied in form 
and life style that we can't choose one that is typical. 
Perhaps we can have the most fun with Pagurus long- 
icarpus, the small hermit-crab. (The last word is hy- 
phenated because these curious animals are not true 
crabs.) Their posterior parts lack the hard, crusty exo- 
skeleton (outside skeleton) of most larger crustaceans; 
they protect themselves by inserting their soft ab- 
domens into a hollow object, generally the shell of a 
snail. This protection is not complete; predatory fish 
swallow them shell and all. 

You can spend fascinating hours observing these en- 
gaging creatures as they scurry over the bottom, drag- 
ging their portable homes with them. You may see two 
hermit-crabs fight over an empty shell, or watch one 
trying to dispossess another — for as the hermit grows it 
must seek larger quarters. Especially amusing are its 
antics as it tries out a series of empty shells; but its 
movements are so quick you won't be able to see just 
how it's done. Naturally, it does not want to remain de- 
fenseless for long. Notice when you pick up a hermit- 
crab that it closes the shell opening with its larger pin- 
cer. Different species utilize the shells of different snails; 


in each case the anterior end of the occupant is modi- 
fied to fit the particular house doorway. For example, 
some West Coast hermits inhabit tooth-shells; their 
right claws are cylindrical in form, snugly fitting the cir- 
cular openings of the shells. Even when they are 
stranded on land between tides, they are closed up so 
tightly that they are in no danger of drying out. 

With the aid of your hand lens, you'll be able to see 
tiny eyes at the ends of Pagurus' eye-stalks. When the 
hermit is closed up in his home, notice how its small 
left claw neatly fills in the part of the shell opening not 
closed by the large claw. If you chance to see a hermit- 
crab out of its shell, examine the posterior end of its 
abdomen; you'll see that the last pair of abdominal ap- 
pendages have been modified into hooks, which serve 
to fasten the crab in its shell. Place it next to an empty 
snail shell in a container of cool bay water and watch it 
back in — or better yet, give it a choice of two or three 
empty shells and observe the selection process. 


The skeleton shrimp, Caprella, is actual- 
ly an amphipod. Although tiny (males 
2 cm, females smaller), it is a voracious 
predator. Besides devouring smaller 
crustaceans, it feeds on algae and other 
minute plants growing on Zostera. The 
20-cm pipefish — as curious a creature 
as the related seahorse, preys on 

The Eelgrass Blight 

What do you suppose would happen to Pagurus and the 
many other animals in this habitat if Zostera should dis- 
appear? In the early 1930s the abundant eelgrass beds on 
the east coast were hit by a disease that almost wiped 
them out. The effects were far-reaching. Flounder fishing 
declined; clams became scarce; pipefish almost disap- 
peared. The American brant, whose diet before 1932 had 
been about 90 percent eelgrass, had much difficulty 
adapting to other plant foods, and many of the birds 
starved to death. But Zostera came back during the 1940s 
and is now abundant enough to support and shelter a rich 
natural community. 


Not so easy to find as Pagurus is the northern pipefish, 
which dwells in the Zostera beds, much of the time 
clinging to the plant's leaves and stems where it is well 
camouflaged. It shares with its close relative the sea- 
horse a curious habit: the eggs are deposited by the 
female in a pouch in the male's underside, where they 
remain until hatching. After hatching, the young pipe- 
fish use the pouch as a retreat in time of danger. 
The pipefish feeds extensively on the amphipod, Ca- 
prella, which preys on the larvae of invertebrates that 
feed on and in the Zostera beds, including some amphi- 
pods that eat the decaying remains of Zostera itself. 

The more you learn about the creatures in this habitat, 
the more you realize that all are interrelated and all are 
dependent on Zostera. But what about the fisherman 
who is, understandably, annoyed when his boat propel- 
ler is fouled by eelgrass? Is he aware that the summer 
flounders he is angling for feed on the pipefish, and 
thus are intricately linked with the plant and all the 
other organisms in the community? 

Can you construct a food chain beginning with Zostera 
and ending with man? (You will find good references 
in the reading list in the back of this booklet.) Tip: 
flounders eat blue crabs. 



Your own community functions through the efforts of many 
persons doing many different jobs. In the same way, each 
organism in a natural community has a role, or niche. All 
green plants are producers, converting raw materials into 
food that supports the animal component of the commu- 
nity; but each plant species has a precise niche. For 
example, beach grass functions in the dune-and-swale 
community to capture moving sand and to stabilize the 
dunes, making it possible for other plants to become 
established. Pitch pines, beach plums, and other woody 
plants not only provide food for insects, cottontails, and 
whitetail deer, but also furnish shelter from sun and wind. 
The cottontail's niche is that of herbivore; it converts plant 
food into flesh. The red fox's niche is not so simple; it is 
predator, herbivore, and scavenger all in one. 


Sometimes two animals seem to be performing the same 
function. But investigation shows that their niches are not 
identical. The long-eared owl and the short-eared owl, 
Asio wilsonianus and Asio flammeus, are a good illustra- 
tion. These closely related birds have almost identical 
diets, the bulk of their food being small rodents. But their 
habits separate their functions in the island's ecology. 
The long-eared owl prefers dense woodland and thicket 
growth, and the short-eared owl prefers more open areas 
such as sand dunes and marshes. Even where their hunt- 
ing ranges overlap they play a different ecological role, 
for the short-eared owl is most active by day and the long- 
eared owl by night. Thus the former feeds on diurnal 
species, the latter on nocturnal. How do the niches of the 
greater yellowlegs and the lesser yellowlegs differ in the 
Fire Island environment? Compare the roles of the white- 
footed mouse and the meadow vole ("field mouse"). 



Adaptation: An inherited structural, functional, or behavioral characteristic 
that improves an organism's chances for survival in a particular habitat. 

Algae (pronounced "AL-jee"): A group of plants (singular, alga, pro- 
nounced "AL-ga"), one-celled or many-celled, having chlorophyll, without 
roots, and living in damp places or in water. 

Brackish Water: Mixed fresh and salt water, as in estuaries and lagoons 
where water from streams mixes with tidal waters. 

Carnivore: An animal that feeds upon the bodies of other animals. (Para- 
sites are not included in this definition.) Animals that feed chiefly upon 
insects are more often referred to as insectivores. 

Commensalism: The relationship between a host plant or animal and its 
"guest," a species that shares the host's food without harming it. The flat- 
worm, Bdelloura, is commensal, not parasitic, on the horseshoe-crab. 

Deposition: The laying down of rock particles, by wind or in water. 

Dune: A hill or ridge of wind-deposited sand. The windward side slopes 
gently, while the lee side is steep. 

Environment: All the external conditions — such as soil, water, air, and 
organisms — surrounding a living thing. 

Erosion: Any process by which materials of the earth's crust are worn 
away or removed from the surface. Water, wind, and gravity are the usual 


Estuary: The portion of a river or coastal wetland affected by the rise and 
fall of the tide, containing a graded mixture of fresh and salt water. 

Habitat: The place where an organism lives; the immediate surroundings, 
living and unliving, of an organism. 

Herbivore: An animal that feeds upon plants. 

Invertebrate: An animal that lacks a vertebral column and internal bones. 

Marsh: A wetland, salt or fresh, where few if any trees and shrubs grow, 
characterized by grasses and sedges; in fresh-water marshes, cattails are 

Phylum (plural phyla): The largest divisions in classification of either the 
plant or the animal kingdom. Man belongs to the Phylum Chordata. Zostera 
belongs to the Phylum Embryophta of the plant kingdom. 

Plankton: The small plants and animals of fresh and salt waters that, lack- 
ing swimming ability, drift more or less at the mercy of currents and form 
the base of the food web in most aquatic ecosystems. 

Predator: An animal that lives by capturing other animals for food. 

Scavenger: An animal that feeds upon dead animals. 

Swamp: A wetland characterized by mosses, shrubs, and trees. Usually 
not covered by water the year around. 


Reading List 

Amos, William H., The Life of the Seashore. McGraw-Hill, 1966. 

Bascom, Willard, Waves and Beaches. Doubleday, 1964. 

Berrill, N. J., The Life of the Ocean. McGraw-Hill, 1966. 

Carson, Rachel, The Edge of the Sea. Houghton Mifflin, 1955. 

Coe, Wesley Roswell, Starfishes, Serpent Stars, Sea Urchins, and Sea 
Cucumbers of the Northeast. Dover, 1972. 

Hay, John, and Peter Farb, The Atlantic Shore. Harper & Row, 1966. 

Milne, Louis J., and Marjorie Milne, The Balance of Nature. Alfred A. Knopf, 

Miner, Roy Waldo, Field Book of Seashore Life. Putnam, 1950. 

Niering, William A., The Life of the Marsh. McGraw-Hill, 1966. 

Ogburn, Charlton, The Winter Beach. Simon & Schuster, 1970. 

Perry, Bill, Our Threatened Wildlife. Coward-McCann, 1969. 

Petry, L, and L. Norman, Beachcomber's Botany. Chatham, 1975. 

Shepherd, Elizabeth, Tracks Between the Tides. Lothrop, Lee, & Shepherd, 

Sterling, Dorothy, The Outer Lands. Natural History Press, 1967. 

Voss, Gilbert L., Oceanography. Golden Press, 1972. 

Q2 Zim > Herbert S., and Hurst H. Shoemaker, Fishes. Golden Press, 1955. 

Zim, Herbert S., and Lester Ingle, Seashores. Golden Press, 1955. 


i B«« 



Using Metrics 

As we go to press with this book, the United States is 
in the early stages of conversion to the metric system 
of measurement. Though we urge you to think metric — 
for most of the world does — we provide this table to 
help you understand the measurements given in the 

Conversion Table 























2.471 1 







Square Miles 





Troy Ounces 






Degrees Celsius 


1.8 and add 32 


Degrees Fahrenheit 







'■> '.*• 














^GPO:1 978-261 -215/8 

For sale by the Superintendent of Documents, U.S. Government Printing 

Office, Washington, DC 20402. Stock Number 024-005-00723-7. 



As the Nation's principal conservation agency, the Department 
of the Interior has responsibility for most of our nationally 
owned public lands and natural resources. This includes 
fostering the wisest use of our land and water resources, 
protecting our fish and wildlife, preserving the environmental 
and cultural values of our national parks and historical places, 
and providing for the enjoyment of life through outdoor 
recreation. The Department assesses our energy and mineral 
resources and works to assure that their development is in 
the best interests of all our people. The Department also has 
a major responsibility for American Indian reservation com- 
munities and for people who live in Island Territories under 
U.S. administration. 





\ / 
\ /